Limited data suggest that physical exercise can reduce impulsivity and can also reduce drug use. However, the mechanism by which these effects may occur is unknown. The overall aim of the proposed research is to understand the effects of exercise on impulsivity and drug use, and to determine whether there is a common mechanism underlying these effects. Three experiments are proposed in rats that use parallel structures to increase the ability of data from each to inform interpretation of the others. Experiment 1 (Aim 1) will determine whether repeated treadmill exercise (3 levels: no exercise, 20 min, 60 min) is associated with decreases in impulsivity (delay discounting). Experiment 2 (Aim 2) will determine whether repeated physical exercise is associated with lower rates of acquisition of cocaine self-administration, and a reduction in sensitivity to the reinforcing efficacy of cocaine determined by examining response rates over a range of cocaine doses. Experiment 3 (Aim 3) will examine the dopaminergic activity in the nucleus accumbens and prefrontal cortex following repeated physical exercise and response to a cocaine challenge, as dopamine and these structures have established roles in impulsivity and in drug self-administration. This research will shed light on the neurobiological and behavioral mechanisms by which exercise might influence drug use, and will provide data that can stimulate clinical studies examining exercise both as a treatment and as a potential prophylactic during adolescence and young adulthood. PUBLIC HEALTH RELEVANCE: The studies will determine whether engaging in regular physical exercise decreases impulsive decision-making, which is a known risk factor for initiating a number of dangerous, unhealthy behaviors, and decreases the likelihood of using cocaine. Studies will also try to identify a mechanism underlying these effects, which could be developed later to supplement and increase the effectiveness of exercise on these behaviors.